Prospects for cooling of marine organisms with the ice using chitosan and its polyelectrolyte complexes

A new cooling medium for storage of fish and seafood is proposed - frozen water solution of polysaccharides of natural origin, as the natural biopolymer chitosan. Rational concentration of its solution for producing the chitosan ice is determined experimentally. Organoleptic, physical, and microbiological parameters of the ice prepared from solution of polyelectrolyte complexes of chitosan and its co-polymers are examined. Better results for cooling of marine raw materials are shown for the solution of polyelectrolyte complexes based on chitosan with sodium alginate and carboxymethyl cellulose. The chitosan-alginate ice is distinguished by higher density and homogeneous consistency within the temperature range from -5 to +5оC. Antiseptic microbiological activity of the chitosan-alginate ice is in 2.3 times higher as compared with the water ice and in 1.8 times higher than for the chitosan ice. High technological properties of the ice of polyelectrolyte complexes of chitosan with sodium alginate provide good prospects for its using in technology of cooling in fishery industry

Bimetallic Layers Increase Sensitivity of Affinity Sensors Based on Surface Plasmon Resonance

Two metals are used in resonant layers for chemical sensors based on surface plasmon resonance (SPR) - gold and silver. Gold displays higher shift of the resonance angle to changes of ambient refraction index and is chemically stable. Silver posses narrower resonance curve thus providing a higher signal/noise ratio of SPR chemical sensors, but has a poor chemical stability. A new structure of resonant metallic film based on bimetallic silver/gold layers (gold as an outer layer) is suggested. It combines advantages of both gold and silver resonant layers. Bimetallic resonant films display so high shift of resonance angle on changes of ambient refraction index as gold films, but show narrower resonance curve, thus providing a higher signal / noise ratio. Additionally, the outer gold layer protects silver against oxidation